Despite his success in television, Slade returned to the theater in 1975 with his play Same Time, Next Year, about a couple who are married to others but meet once-a-year for sex and conversation. With Charles Grodin and Ellen Burstyn in the leads, the play was a major hit and ran for 1453 performances. Slade received the Drama Desk Award and a Tony Award nomination for Best Play. In 1978, he followed with Tribute, the story of a man who learns to love his father, a successful actor who always had more time for his theatrical cohorts than his son. Even with Jack Lemmon heading the cast, it proved to be far less successful than its predecessor, closing after 212 performances. Slightly more successful was Romantic Comedy (1979), starring Anthony Perkins and Mia Farrow. Slade wrote the screenplays for the film versions of all three plays, and was Oscar-nominated for his screen adaptation of Same Time, Next Year.